A comfortable humidity level for an average person ranges between 30% and 65-70%, depending on activity, but the recommended humidity level is between 30% and 50%.
When there is a insufficient moisture in the air, nose, throat and skin feel dry and scratchy (makes the mucous membranes inside the nose and throat , organism's first barrier against airborne infections, dry and more susceptible to diseases)
Low humidity, also, makes mucus produced by sinuses membrane to be thicker and more likely to block sinus openings, thus causing pressure inside the sinus cavities that leads to sinus headaches.

Have you thought of using water sprayers or humidifier at your office, or you can simply turn off the excessive air conditioning?

Thank you for your reply. A couple years ago I tried using a humidifier on my desk at work. It was simply unable to compete with the building HVAC system. It was a residential sized humidifier and my desk is in a cubicle farm on something like a 2000 sq foot open-plan office floor.

Also at the time I brought in a little humidistat, the kind that's intended to measure humidity in a basement. It typically started out in the morning at around 25% and was often down to 19% by afternoon.

Once I emailed our building managers to ask about the humidity and if they had any control over it. She replied that they don't, and that they try very hard to take humidity OUT of the air, not put it back in. I thought that was very stupid (but I didn't reply back to her saying that). In the U.S. northeast area summers are humid but winters are dry. If you take already dry winter air and dry it even further with the building HVAC, you get Sahara conditions in your office.

I've been very frustrated with this in an otherwise terrific workplace. It doesn't seem to bother my coworkers, which makes me feel like a prima dona. Maybe I can use it as an excuse to start a home office, but I don't know how well they'll take it.

You can complete some papers with medical informations via internet about relation between humidity and medical issues and give it to your manager.
Also, it will be helpful to get a written opinion from your GP or surgeon with medical explanation about working place affecting your health.
Definitely, you can use it as a excuse to work at home or building managers will need to take in consideration turning off the excessive air conditioning.

Waiting for your post!
Best wishes!
Marija